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new motor useing alot of oil.

fattyboy

Active Member
Hi all its been awhile,Still working on the fatboy 113cu..Just had it rebuilt new pistons rings crank and had it bored 30 over.the cyls. are what they call bigger bore cyls.it has woods cams 9fg.in which make alot of top end noise!!!But anyways the problum iam having is i have 400 miles on it and its almost a qt low,its not smoking that i can see.but i can take and wipe mfinger in the end of the exh.and its real black and very wet.the motor runs fine,never took it up to 55miles hour and held it their,I did just like they said change the speed back and forth.Please help with any ideas!
 
First place to check is your spark plugs. How do they look?

If they are carboned up and black and wet, you've got oil leaking past your pistons or your valves. From the noisy top end you mention, I'd look at the valves.

You certainly don't want to be running it in the condition it's in.
 
Who did the build? How did the pistons fit? Are the rings installed correct? The list will go on. Can you supply more info? Even a new not broke in engine should be down 1 qt of oil and the pipes should not be wet or oily inside yet
 
Time for a compression and leak down test. There are many reasons for the excessive oil consumption but you have to start with a baseline that establishes the condition of the top end.:D
 
I did a compression ck. and both cyls. where 150.I took a bore scope and looked in the cyls.the top of the pistons had alittle bit of burnt oil on them and i looked at the valves and the front cyl.the one valve was light brown and the other valve was a real light gray,The same with the other cyl..
 
I did a compression ck. and both cyls. where 150.I took a bore scope and looked in the cyls.the top of the pistons had alittle bit of burnt oil on them and i looked at the valves and the front cyl.the one valve was light brown and the other valve was a real light gray,The same with the other cyl..

Is the 113" a 4.060" x 4.375" or 4.250" x 4" configuration? What head gasket thickness? Have the heads been decked? You need to run all that through a compression calculator and compare actual with calculated. The 9fg cam has a very late intake close so compression could be that low but I would have expected at least to see 170psi or 185 psi depending on the bore/stroke. You need to do a leak down test.

What you see with the bore scope doesn't sound alarming and would point me to the rings. A broken ring, a ring upside down, etc.:newsmile08:
 
Kind of elementary, but, if the oil scavenging rings are installed upside down, you will get high consumption.

Good luck,
Rich P
 
Is it carb or FI. I bought a set of heads last year that had carboned up exh valve guides and a lot of oil on the backside of the intakes.We think that it was carb and run with to much choke too long. Sucking a lot of oil thru intake guide. Also may want to check your primary oil level. Oil can be leaking into primary from the engine if the seal, spacer and or thrust washer have a sealing issue.
 
Put it on the interstate and ride it all day the rings will seat. Constant heat soak may be what you need to make the rings take shape.
 
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